This invention relates to pressurized fluid product dispensing apparatus. More particularly, it relates to apparatus for pressure dispensing of fluid products, including very fine powders, without the use of pressurizing gases or propellant gases, in which the dispensing pressure is supplied by the inherent contracting force of an expanded elastomeric pressure unit.
Pressurized product dispensing containers have become exceedingly popular in recent years. Since its inception, the popularity of this mode of packaging has consistently increased, resulting in the present day availability of numerous products in pressure dispersed or aerosol form. There are, however, certain difficulties with existing pressure dispensing systems. The propellant gas in aerosol dispensers is relatively expensive, and often must be used in equal proportion to the product to be dispensed. Additionally an air space of 20-30% of the volume of the container must be provided for gas expansion under varying thermal conditions as a safety feature. This requires the use of a relatively large container for carrying a small amount of product, resulting in extra expense for container materials and pressurizing gas, and in inefficient space utilization.
In addition, effective gas propellants are sometimes not compatible with certain products, especially foods. Further, aerosol containers are somewhat hazardous since they can explode when subjected to heat or puncture.
More recently, there have been indications that the fluoro-carbon propellant gases which are used in the majority of aerosol containers are incompatible with the upper atmosphere's ozone layer which provides essential protection for the earth from excessive ultraviolet radiation. As a result, environmental groups have called for government legislation banning the use of fluoro-carbon propellant gases and have urged the public to refrain from buying aerosol products utilizing such gases. Substitute aerosol propellant gases are not readily available since the extremely low chemical activity of fluoro-carbon gases makes them uniquely compatible with many aerosol products. Therefore, if many aerosol products are to continue to be available, it appears that some gasless dispensing system must be substituted for the present pressurized aerosol systems. Alternative dispensing systems such as finger or trigger type fluid pumps have proved too expensive and unreliable.
It has been suggested in the prior art to use bladders, or pressure units, of elastic material positioned interiorly of containers as a means of dispensing fluid products. In my co-pending application, Ser. No. 378,886, is shown such a fluid dispensing system including a pressure unit of elastomeric material, having an upper tubular portion with its annular surface bonded to a valve support and including means carried by the pressure unit for stiffening the tubular portion of the elastomeric material adjacent to the bonded area, which provides a unique and efficacious gasless product dispensing system.
While apparatus such as shown in my co-pending application provides an entirely satisfactory gasless pressure dispensing system for a wide range of fluid products, there are certain products which are chemically incompatible with the elastomeric material of the pressure unit, or which might tend to pick up an undesirable odor or flavor from the pressure unit's elastomeric material. For certain applications, it is therefore preferable to provide in connection with such a dispensing system, means for separating the product from the elastomeric material of the pressure unit.
It is accordingly, the primary object of the present invention to provide a gasless pressurized product dispensing apparatus in which the dispensing pressure is supplied by the inherent contracting force of an expanded elastomeric pressure unit, which apparatus includes means for containing the product to be dispensed so that said product is protected from contact with the elastomeric material of the pressure unit.
Another object is to provide such an apparatus which is relatively simple and inexpensive to manufacture.
Another object is to provide such an apparatus having a flexible bag which also functions as a liner surrounded by an elastomeric pressure unit, with the bag or liner formed of any suitable material compatible with the product to be dispensed and containing the fluid or other product to be dispensed and serving to separate the fluid from the elastomeric material of the pressure unit.
A particular object is to provide a flexible bag which is of such size that when it is filled with product and the elastomeric pressure unit is expanded, said bag engages the inner wall of the unit to form a liner supported by the pressure unit; said liner functioning to prevent contact of the product with the elastomeric material of the pressure unit.
A further object is to provide such an apparatus which is readily applicable to conventional dispensing valves and containers for pressure dispensed products and which will dispense almost all of the product since most lines materials will fill the core of the pressure unit when it returns to its original relaxed position.